The following are known as fluorinating agents for fluorinating organic compounds: HF, KF, IF, IF5, tetrabutylammonium fluoride, tris(dimethylamino)sulfur(trimethylsilyl)difluoride (TASF), SF4, diethylaminosulfurtrifluoride (DAST), fluorine gas, XeF2, CF3OF, CH3COOF, ClO3F, N-fluoropyridinium triflate, 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate), 1-hydroxy-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate), N-fluorobenzenesulfonimide, etc. (Sheppard, W. A.; Sharts, C. M. Organic Fluorine Chemistry, 1969, W. A. Benjamin: Chambers, R. D.; Fluorine in Organic Chemistry, 1973, Wiley-Interscience: Hudlicky, M. Chemistry of Organic Fluorine Compounds, 1976, Ellis Horwood: Hudlicky; M. and Pavlath, A. E., Chemistry of Organic Fluorine Compounds II, 1995, ACS Monograph 187: N. Ishikawa and Y. Kobayashi, Fluorinated compounds-Chemistry and their application, 1979, Kodansha Ltd.: Outline of chemistry/New fluorine chemistry, 1980, Japan Scientific Societys Press: N. Ishikawa, T. Kitazume, and A. Takaoka, Journal of the Society of Synthetic Organic Chemistry, 1979, 37, 606: T. Umemoto, Journal of the Society of Synthetic Organic Chemistry, 1992, 50, 338: S. D. Taylor, C. C. Kotoris, and G. Hum; Tetrahedron, 1999, 55, 12431: Japanese Unexamined Patent Publication No. 1997-227531, etc.)
Among those fluorinating agents, HF, KF, IF, tetrabutylammonium fluoride, and sulfoniumsilicate (TASF) have low reactivity, and therefore have limited uses. SF4 is a toxic gas having a boiling point at −40.4° C., which is difficult to handle. Fluorine gas is so active that it is difficult to control its reaction. Furthermore, it is reported that CF3OF, CH3COOF, and ClO3F are explosive gases and should be handled with caution. Diethylaminosulfurtrifluoride (DAST), XeF2, N-fluoropyridinium triflate, 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate), 1-hydroxy-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate), N-fluorobenzenesulfonimide, etc., are easy to handle and enable selective fluorination; however, they are expensive reagents and this causes a problem in using them for industrial purposes.
IF5 is an industrially usable fluorinating agent that is a nonexplosive and easy-to-handle liquid having a boiling point at 100.5° C. and a melting point at 9.4° C. Fluorination using IF5 is employed only in a process of adding IF to perfluoroolefin and substituting iodine of the perfluoroiodoolefin with fluorine (M. Sakai, Organic Fluorine Chemistry I, 1970, pp 348-351, GIHODO SHUPPAN Co., Ltd.: A. A. Banks, H. J. Haszeldine, and V. Kerrigan, J. Chem. Soc., 1948, 2188: R. D. Chambers, W. K. R. Musgrave, and J. Savory, J. Chem. Soc., 1961, 3779). However, since it is difficult to control its high oxidizing property, using IF5 for fluorinating organic compounds that have hydroxyl groups, carbonyl groups, etc., was hitherto not known.